Battery wears down after a couple of days

[matt_vo]

Hey all,
I don't know if anyone can suggest something.
Here's the deal. Whenever I leave the car parked for a couple of days, the battery runs out and I can't start the car. It's not the alternator cause the car runs after I boost it, and it charges the battery if I use the car for a while.
- Would this be due to my battery, which is 4 yrs old?
- Or to the fact that I don't use my car much often and it sits there during the week? I use it on weekends usually. I'm not sure about this because I've had my car for the last year and it's just starting to do this.
- Or an electrical short somewhere that's draining the battery? If this is the case, and I charge my battery by running the car, can I unplug a terminal from the battery whenever I let it sit there during the week so that it doesn't drain?

Thanks all,
Matt

[jlevie]

It could be the battery, have it tested.

It also could be a weak alternator and you can check that with a DMM. At idle you should see something in excess of 13.6v, rising to 14.0 or more at 2500rpm.

Or it could be excessive parasitic draw (the current draw from the battery with the engine shut down). Normal parasitic draw would be in the 30-6ma range and you check that by placing an ammeter (I use an auto ranging DMM) in the negative connection from the battery.